Coumaran derivatives and process for preparing same



Patented May 9, 1950 UNITED srArEs PATENT 2,507,473 OFFICE COUMARAN DERIVATIVES AND PROCESS FOR PREPARING SAME Charles Frederick Koclsch, St. Paul, Minn.,' assignor to Smith, Kline A: French Laboratories, Philadelphia, Pa., a corporation of Pennsylvania No Drawing. Application January 3, 1946, Serial No. 638,917 2 Claims. (Cl. 260-446) molecular rearrangement, whereas as applied according to the method of this invention an intramolecular rearrangement is accomplished.

More specifically, the novel compounds comprehended according to this invention will have the structure made apparent by the following formula:

in which R and R are members of the group consisting of H, an alkyl group, an oxygen-containing alkyl group resulting from the substitution of an oxygen atom between two of the carbon atoms of an alkyl chain, as, for example, CH3OCH2CH2-, and a nitrogen-containing alkyl chain, as, for example, (CI-I93 N CH2CH2; or R and R together are members of the group consisting of a polymethylene chain, as, for example, -CH2CH2CH2-, a polymethylene chain having 0 between two of the carbon atoms, as, for example, -CH2CH2OCH2, and a polymethylene chain having an alkyl amine group between two of the carbon atoms, as, for example,

$113 CH;CH2N-CH,- X and X are members of the group consisting of R=alkyl less than C10, or aryl, and COOR, R= alkyl less than C5; X is a member of the group consisting of H, an alkyl group, an alkoxy group and a halogen group and Y is a member of the group consisting of Specific compounds within the purview of this invention from the broad standpoint will be made apparent in connection with the following description of the method according to this invention and specific illustration of its adaption to the production of specific compounds.

As has been indicated, the method according to this invention involves the application of the 2 Michael reaction, 1. e., treatment of a particular starting material with basic catalyst, more specifically, an alkali metal or an alkali metal derivative, with or without a solvent or with or without the application of heat with resultant intramolecular rearrangement or, more specifically, rearrangement of the bonds between atoms within a molecule resulting in the formation of a new ring.

The starting material for carrying out the method according to this invention will be a compound having the following structure:

CHPX

KAY/ in' which R and R are members of the group consisting of H, an alkyl group, an oxygen-containing alkyl group resulting from the substitution of an oxygen atom between two of the carbon atoms of an alkyl chain, as, for example, CHaOCHzCI-lzand a nitrogen-containing alkyl chain, as, for example, (CH3) 2 N CH2CH2; or R and R together are members of the group consisting of a polymethylene chain, as, for example, CH2CH2CH2-, a polymethylene chain having 0 between two of the carbon atoms, as, for example,

X and X are members of the group consisting of l GN, R-CO R=alkyl less than C10, or aryl and COOR, R= alkyl less than C5; X is a member of the group consisting of H, an alkyl group, an alkoxy group *and a halogen group and Y is a member of the group consisting of ylmethyl lithium, and the like: an alkali metal derivative of ammonia, as, for example, sodamid,

potassium amid, and the like, or other equiva lent alkali metal compound. I

In carrying out the reaction, a solvent for the catalyst and starting material will desirably be medwherethestartinamaterialandcatalystare solids, and, in general, the use of a solvent will be convenient. As solvents,for example, ethanol, methanol, ether and dioxane may variously be used.

In carrying out the reaction, if desired, heat may be applied to promote the reaction, but the application of heat will not be essential, it being noted that heat will be given off in the reaction.

When the reaction is complete, the product will be recovered, after pouring into water, acidifying to neutralize the alkali metal, if a solid, by filtration, and if a liquid, by extraction, for example, with ether, benzene, chloroform, or other water-immiscible solvent, followed by removal of the solvent.

The product, if liquid, will be purified by distillation and, if solid, by recrystallization from a solvent, as ether, benzene, chloroform, or other suitable solvent.

The procedure according to the method of this invention in detail and specific products within the scope of this invention will be illustrated and made clear by the following examples:

Example 1 For the preparation of ethyl 2-carbethoxycoumaran-3-acetate, a solution of 0.25 g. of sodium in 4 ml. of dry ethanol is added to 14 g. of ethyl coumarate-O-acetate (a known compound) at 25 C. The mixture becomes a deep yellow color and its temperature will rise to about 75 C. After warming the mixture on a water bath for some fifteen minutes, it is neutralized with aqueous acetic acid and the product extracted with ether, neutralized with dilute sodium carbonate and the neutral product purified by distillation. The product was found to boil at l91-l93 C. at mm. mercury and to analyze as follows:

Calculated for CHHHO Found 0,134.8 C, .6 H, 6.5 H, 6.8

Example 2 Calculated for (Mano. Found Example 3 For the preparation of 2-carbethoxy-3,6-dimethylcoumaran-3-acetate. 2 g. of ethyl 4,p-di methylcoumarinate-O-acetate at 53 C. are treated with a few drops of alcoholic sodium ethoxide. The mixture becomes dark red and its temperature rises to about 100 C. The product, 2-carbethoxy-3,6-dimethylcoumaran-3-acetate, having 4 a boiling point of 195-196 C. at 9 mm. mercury, is recovered in a manner similar to Example 1 and analyzed as follows:

Calculated for CnHnOl Found Example 4 For the preparation of ethyl 2-carbethoxy-3,6- dimethylcoumaran-3,a-butyrate, 2 g. of ethyl a-ethyl-4,;s-dimethylcoumarinate-O-acetate are warmed to about 45 C. and treated with a few drops of alcoholic sodium ethoxide. The mixture becomes dark and its temperature rises to about C. The product, ethyl 2-carbethoxy- 3,6-dimethylcoumaran-3,c-butyrate, having a boiling point of 20'l210 C. at 13 mm. mercury. is recovered in a manner similar to Example 1 and analyzes as follows:

Calculated for cnHmol Found C, 68.3 C, 68.1 H, 7.3 H, 1.9

Example 5 Calculated for OnHnOs Found C, 68.7 C, 68.9 H, 7.2 H, 7.4

It will now be observed that according to this invention it has been found that by the treatment as described of the compounds defined above as starting material, an intramolecular reaction occurs with the formation of an additional ring, in distinction from an intermolecular reaction, as heretofore occurred in application of the Michael reaction. Further, it has been found that the intramolecular reaction accomplished, unlike the intermolecular reaction, is not inhibited by alkyl constituents on aand fi-carbon atoms of the acceptor group and the reaction apparently goes substantially to completion.

What I claim and desire to protect by Letters Patent is: l

1. A compound having the following structure:

X and X are selected from the group consisting of carbalkoxy groups not in excess of five carbon v 5 atoms and X is a member of the group consisting of hydrogen, lower alkyl groups and lower alkoxy groups.

2. The method of preparinga, compound having the following structure:

R1 c-cri-x x in in which R and R are selected from the group consisting of hydrogen and lower alkyl groups;

, X and X? are selected from the group consisting of carbalkoxy groups not in excess of five carbon atoms and X is a member of thegroup consisting of hydrogen, lower alkyl groups and lower al-- koxy groups, which comprises treating a compound having the structure:

' 10 Number where R R X X and X are as given above, with a basic catalyst.

CHARLES FREDERICK KOELSCH.

REFERENCES CITED The following referencesare of record in the file 01 this patent:

UNITED STATES PATENTS Name Date 7 714,042 Seifert et al Nov. 18, 1902 OTHER REFERENCES Richters Organic Chemistry 1923), vol. 3,

15 page 39. 

1. A COMPOUND HAVING THE FOLLOWING STRUCTURE: 